Many systems and devices have been developed for sensitive and quantitative detections for biological data applications. For example, a technology called Enzyme Linked Immunosorbent Assay (ELISA) is one of the more popular detection devices. ELISA applies a technique called a quantitative sandwich immunoassay. If a target such as IL-10 cytokine is present in a sample, it binds and becomes immobilized by an antibody pre-coated and “sandwiched” by biotin conjugate. To quantitatively determine the amount of IL-10 present in the sample, Avidin conjugated to Horseradish Peroxidase (HRP) is added to the detection microplate. The final combination of IL-10, biotin-conjugated antibody and enzyme-conjugated Avidin exhibits a change in color.
The color change is then measured spectrophotometrically as Optical Density (O.D.) at various wavelengths such as 450 nm, 492 nm or 620 nm. The concentration of IL-10 in the sample is then determined by the standard corresponding curve between the measured O.D. and the real concentration.
However this detection device has several disadvantages. For example, ELISA can only detect one target in each assay. Moreover, the detection time could be from 8 hours to over 20 hours. Additionally, the dimensions of width, length and height of the spectrum based reader device are normally around 10, 10 and 5 inches.
Another multi-target, sandwich type lateral flow assay has been developed based on Nano-Intelligent Detection System (NIDS). This multiplexed test format allows rapid detection of multi targets in few minutes. FIGS. 1A and 1B respectively illustrate top view and a side view of a lateral flow-based immunoassay ticket configuration. An adsorbent pad a receives a sample target and a conjugate release pad b includes a conjugate comprising of gold and antibody embedded therein. The sample passes through the conjugate release pad b and flows on a membrane c by a capillary flow. A zone d contains capture antibody (testing line), where antibody-antigen-antibody-gold complex (sandwich) is formed. A zone e containing control antibody where a control line is formed through direct antibody against another antispecies antibody. A receiving pad f receives liquid from the membrane c.
FIG. 2 is an illustration of positive and negative immunoassay tickets. The assay includes four components: a capture antibody, an antigen, a detector antibody for binding the target, and a labeled reporter molecule of interest which binds to the detector antibody. The sample liquid is added into one or more sample well(S). The control points or lines determine if the ticket itself is a functional ticket. In other words, if the control lines/points do not appear, the ticket is a bad ticket, regardless of the sample. For negative sample results, only control points or lines appear in the control zone c. For positive sample results, in addition to the control points or lines, there are target points or lines appearing in the target zone/area (T). The ticket window area in FIG. 2 is the inner rectangle that includes the control zone/area and the target zone/area.
The reporter can be an enzyme, a fluorophore, a colored particle, a dyed particle, a particle containing a dye, a stained particle, a radioactive label, quantum dots, nanocrystals, up-converting phosphorescent particles, metal sols, fluorophore or dye containing polymer or latex beads that are detectable visually and/or with mechanical assistance and the like.
Such an assay often requires three separate experimental steps. The first step involves immobilization of the capture antibody and reversibly binding the detector antibody on a solid surface, followed by a subsequent addition of an antigen solution to form an antibody-antigen complex. The last step is to add a reporter group comprising a labeled detector molecule or structure to generate a capture antibody-antigen-detector antibody reporter complex.
Therefore, there is a need to an efficient and accurate image-based biological data quantification device and apparatus.